The preparation of hydrogels via peptide self-assembly allows one to define ultimate biomaterial properties by design of individual constituent molecules. Chemical functionality, material morphology, viscoelasticity and processibility can be designed at the molecular level of a self-assembling system. Herein, peptides are designed to intramolecularly fold in response to external stimuli into beta-hairpin conformations that are capable of self-assembling. Folded hairpins assemble into dilute but rigid hydrogels exhibiting porosity on the nano- to -microscale. Triggered folding allows temporal and spatial control of material formation. Gelation will be triggered by various physiologically relevant stimuli; e.g. pH, salt, calcium ions, temperature and light. The chemically benign folding/self-assembly strategy, and the inherent peptidic nature of the resultant hydrogels, provide a potential tissue engineering substrate for fibroblasts and osteoblasts. Peptide design principles leading to rigid, porous hydrogels capable of supporting cell adhesion and proliferation will be determined by directly observing how peptide structure affects the self-assembly process, material morphology, material properties and cytocompatibility. The interdisciplinary "molecular to materials" design and properties characterization of the proposed hydrogelation system will be accomplished via close collaboration between the chemistry/biochemistry and materials science and engineering departments. This research effort will: 1. Gain a fundamental understanding of the folding and self-assembly process leading to hydrogel formation and how molecular design affects material properties. 2. Enhance the processibility of hairpin-based hydrogels by designing active intramolecular folding triggers that allow peptide solutions to undergo hydrogelation on cue. 3. Determine how peptide structure and material properties affect the adhesion and proliferation of model fibroblast and osteoblast cell lines.